(()=>{
    interface IPerson{
        firstName:string,
        lastName:string
    }
    function showName(params:IPerson) {
        return params.firstName +'_'+params.lastName
    }
    //define a object
    const person ={
        firstName :"东方",
        lastName: "不败"
    }
    console.log(showName(person));
    
})()